I do not have an operations manual nor can I find one online that will tell me what it means when my Criterion II heater has a LED light that flashes 4 times and will not kick on. I can get the heater to come on by jiggling wires, but once it goes off again, it will not come back on. The heater is not that old and I would love to know what it means when the LED indicator blinks 4 times. That is what happens when it doesn't come back on.
Thanks, MJB

4 blinks could be flame signal, does the (amber) led come on when furnace does ignite, if not clean flame sensor (make sure the ceramic is not cracked) use emery cloth or steel wool to clean, it could also mean open limit but if it fires at all this is not likely. I believe on that model you have 3 lights, 1 is power (green), 1 is flame signal (amber), the other is the diagnostic code (green) that is blinking 4 times. It should tell you on the panel by the schematic what that code is.
Check the polarity coming into the furnace this is very important. Also the ground, push in on all electrical harness plugs to make sure you have good connection.
You are experiencing what is called a lock out, this is what happens when something goes wrong and then the diagnostic light begins to flash. You reset it by turning the power off to the unit and back on again.

The same thing happened to me and do not waste your time calling Rheem/Ruud Customer Service because they will not assist the end user, (speaks volume about this companies commitment to its customers doesn't it).

In my case I traced the problem to the "pressure switch" which a black circular disk located in the top left corner of the "burner compartment" for lack of a better description. Jiggle the wires connected to it and see if the furnace comes on. If it does then it is indeed the "pressure switch." Find the model # on the pressure switch, 42-24335-03, for example and search for a replacement. The part number may have changed like it did in my case so you will have to cross reference it. The original part # on mine was 42-24335-03 and the new part # is 42-24194-82. I found my replacement pressure switch on www.simplyplumbing.com for $29. It took me 5 minutes to replace and it the furnace is back to normal operating condition. This seems to be a common problem with these furnaces from my research! Thanks for the warranty recall Rheem (whose names seems appropriate)!

I saved a bundle as the Rheed/Ruud repairmen wanted to come out and diagnose the problem, then order the part (which I am sure would have cost 3 times what I paid) then come back and install it. I saved over $300 -$400 by doing this simple task by myself. I hope this helps!

My Rudd/Rheem Criterion II gas furnace was part of a duel fuel hvac system. When the outside temps got to around 25-30 degrees the heat pump would seem to run forever before it would warm up the house. I found I could solve this problem by switching the system over to gas/emer heat until the outside temps would get warmer or colder to satisfy automatic demands. I woke up several nights in a cold house to find out the thermostat was calling for heat in a proper manner but the furnace wasn't responding. My problem was intermittent. Sometimes I would have this problem and sometimes not but the entire system seemed to work okay as long as I left the thermostat on "AUTO". I was getting the 4 blinks of the diagnostic code lamp which indicates "pressure switch closed" when the furnace failed to kick on. Fault lamp codes can be found in "Figure 28 Trouble shooting flowchart" notes which is in the "Installation Instructions" manual left with the HVAC system. I also figured out that if I tapped on the pressure switch that the furnace would kick on.

I found info in this web site to be helpful and I wanted to add my posting. As safronek said before me my original pressure switch part was 42-24335-03. I ordered a new pressure switch from Arnoldservice.com. The new kit part was 42-24194-82. I only had to use the pressure switch. I did not need the hose or straps. There is a little confusion in the electrical terminals. The terminal configuration is not the same on the new pressure switch as the old. I put the brown wire on what looks like the "NO" terminal of the new pressure switch and the purple wire on the other one. The furnace seems to be working okay and I have not had the intermittent problem as before. Thanks very much for the previous posts and help.

tiltec